package Temp.杂乱无章;

import java.util.Scanner;

/**
 * 求圆的面积
 * 2023/11/28已完成
 */
public class 圆面积 {
    public static void main(String[] args)
    {
        float S;
        float L;
        Scanner scanner = new Scanner(System.in);
        float r = scanner.nextInt();
        S = (float) (3.14 * r * r);
        L = (float) (2* 3.14 * r);
        System.out.println(S);
    }
}






